Also I notice, that awesome's memory use grows continuously with uptime. After start it uses only 9-10MB, but for moments of crash it uses more than 30MB memory. May be this not connected with crash, but I suppose that such behavior isn't normal for WM program.

There were two commits which fixed some memory leaks on the lua stack. Those bugs could cause something like this. The leak happened on every focus change and every NET_WM_PROPERTIES change, so that would definitely sound like "high uptime".

I hope that this is fixed in git now and just close this for now, feel free to reopen if this still happens. (FYI, no release of awesome contains this fixes yet, wait for the next one)

In general, all goes like in previous versions. Three or four times a day awesome just restarts (and loses all manual adjustments to (custom) rc.lua configuration )-:E
I cannot say this happens less frequently in 3.4.4 — may be, but I haven't noticed it.